Joe Swanberg has long been a director whose films have been more widely talked about than actually seen. He has become controversial for his improvisational style of ultra-low-budget filmmaking, his frank depictions of sexuality and his central position in the oeuvre known as "mumblecore."

Following his first film, "Kissing on the Mouth," in 2005, Swanberg began to really break through with 2007's "Hannah Takes the Stairs" and 2009's "Alexander the Last," examinations of the foibles of self-discovery within the post-collegiate creative class. Swanberg's circles have been a crucible for emerging actors and filmmakers who have gone on to bigger things, including Greta Gerwig, Lena Dunham, Mark and Jay Duplass, Lynn Shelton and Ti West.

Yet rather than using his acclaim to move on to higher-profile projects, Swanberg burrowed deeper into personal exploration. Ultra prolific, a selection of his output from 2011 was released as a four-film boxed set, including the intense psychodramas "Silver Bullets" and "The Zone."

But his latest work, "Drinking Buddies," which opened Friday in Los Angeles, seems to mark a new phase for the filmmaker.

For the first time, he is working with a cast of known names: Olivia Wilde, Jake Johnson, Ron Livingston and Anna Kendrick. The movie, which is also available on video-on-demand, looks like it will be his biggest commercial hit. And after years of essentially growing up in public, often purposefully doing the unexpected, he's made a movie that could be recognized as a romantic comedy.

"I very much was" an angry young man of American independent cinema, conceded Swanberg, who turns 32 Saturday. "It's interesting thinking back on it, I can't remember why, other than I think I sensed that the industry needed to change. It was worth telling real stories about people my own age. And then the thing that happened is in the last decade the industry has changed.

"We mumblecore filmmakers made an impact. These people are now cultural figures. Mark Duplass is a famous actor now and incredibly successful film producer and director. Lena Dunham is an icon at this point. Greta Gerwig is a very famous actor. It worked, whatever thing we were doing."

Set amid the craft beer scene in Chicago (where Swanberg lives with his wife and young son), "Drinking Buddies" maintains the loose process and emotional acuity of his earlier work but hews more or less to the structure of a rom-com. The story revolves around the extended flirtation of Kate (Wilde) and Luke (Johnson), who work together at a small brewery. That she has a boyfriend, Chris (Livingston), and he a girlfriend, Jill (Kendrick), is only one impediment to igniting the obvious spark between them.

Swanberg got the film going without even a written outline — just a series of emails and phone calls leading to Skype conversations and meetings with his actors.

"He's supremely confident," said Livingston. "He's got the confidence of a guy that's made 17 or 25 movies. Most people who've made 17 or 25 movies are not Joe's age. So he has the confidence of a much older director. Because he's earned it. And there is something reassuring about that. You feel you're in the hands of a filmmaker."

Said Johnson: "Joe sold me on a lot of ideals. And everything he said, from Day One until today, he's backed up."

Working with "Tiny Furniture" producer Alicia Van Couvering and "Beasts of the Southern Wild" cinematographer Ben Richardson, Swanberg for the first time had proper production departments and a crew of more than just a few people. The $60,000 it took to make "Hannah Takes the Stairs" was Swanberg's biggest previous production, making even the modest budget of "Drinking Buddies," made for less than $1 million, exponentially bigger than what he was used to. Wilde, for example, arrived in Chicago thinking she would be sleeping on Swanberg's couch. (Not necessary, as it turned out.)

Swanberg allowed each of the leads to pick the name of their characters, strengthening their sense of personal connection. At an informal news conference for "Drinking Buddies" after its premiere at the South by Southwest Film Festival in Austin, Texas, this spring, the actors spoke of their characters not as fictional constructs but as if they were people they knew, with quirky psychology and idiosyncratic motivations to match.

In a more recent interview, Wilde noted that her fiancé, actor Jason Sudeikis (who has a small, uncredited role in the film), encouraged her to work with Swanberg after they watched a number of the director's films together, notably his collaborations with Gerwig, including "Hannah" and "Nights and Weekends."

"I really liked how he approached female characters," said Wilde. "Greta's characters in her films with him were always complex and felt very real to me. I don't think many directors allow for that complexity of a realistic female character. And Joe appreciates that."

"Well, I'm curious about them," said Swanberg of his depictions of female characters. "I know what it's like to be a guy, so stories about guys are not that interesting to me. I get it. I have no idea what it's like to be a woman. Those tend to be the stories I want to tell just because I can learn the most."

The cast responded well to Swanberg's improvisational methods. Wilde's skinny-dipping scene, for example, was her own invention. Johnson, Kendrick and Wilde are genuinely a bit tipsy in a few scenes. A pivotal moment between Kendrick and Livingston wasn't planned in advance and was shot only once, but Swanberg felt they'd captured what the story needed.

"He has a vision and can explain it very clearly," said Kendrick. He "just wants everything to be super chill. It sounds silly, but as opposed to a director over-explaining every frame, it's nice when somebody is very accepting of what the reality is on the day and what you end up finding together."

Swanberg remains extremely busy. He appeared as an actor in the recent release "You're Next" and acted in two films that will premiere at the upcoming Toronto International Film Festival. He has two final pre-"Buddies" projects awaiting release, "24 Exposures" and "All the Light in the Sky," and is completing "Happy Christmas," starring Kendrick, Dunham, Melanie Lynskey and Mark Webber. Swanberg was recently offered his first for-hire television directing job and just sold a pitch to Fox Searchlight.

Whatever he's doing differently, it seems to be working.

"I'm not afraid to fail. Making a bad movie does not scare me," said Swanberg. "Every mean thing that could be written about me has already been written. I've already been poor for 10 years and made movies that nobody saw. Going back to that doesn't scare me. So I'm at a playful, experimental point right now. What's the worst thing that could happen?"